Method for enhanced aerobic activity and bio-mat control for onsite wastewater disposal systems

ABSTRACT

The present invention provides an aeration lateral system designated to be site specific for new septic disposal areas or retro fitting to existing septic disposal areas to break up the biological clogging slug mat at the interface of the wastewater and imported sand or native soil fill under or adjacent to disposal areas of a typical septic system. The lateral system provides uniform or other site specific distribution of fluids about the bio-mat of a wastewater disposal area, with lateral spacing and hole spacing varying based on the type of disposal area being utilized. The lateral system can also be utilized to provide continuous low volume air supply system to a wastewater disposal area or peat filter module. The air lateral installation includes methods to minimize airflow disturbance of the soil and methods to prevent air leakage.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/643,243, filed on Mar. 10, 2015, now U.S. Pat. No. 9,352,991, whichis a continuation of U.S. patent application Ser. No. 13/218,758, filedon Aug. 26, 2011, now U.S. Pat. No. 8,974,670, which claims priority toU.S. Provisional Application No. 61/377,178, filed on Aug. 26, 2010, thecontents of which are incorporated by reference herein.

FIELD OF THE INVENTION

This invention relates to enhance aeration of an onsite wastewaterdisposal area located after a primary treatment (settling tank/septictank/aerobic tank).

BACKGROUND OF THE INVENTION

A typical septic system includes septic/aerobic tank or a septic/aerobictank and pump tank where primary treatment of wastewater takes place.The effluent wastewater then flows to a disposal area, buried in thesoil, for secondary treatment and disposal into the ground. Inconventional septic systems, the disposal area can include a disposalbed or trenches with stone and pipe laterals, or a disposal bed ortrenches with infiltration chambers, or seepage pits. Secondarytreatment of wastewater will typically naturally occur at the interfacebetween the disposal area and the soil adjacent to or below the disposalarea. This soil may be imported sand, native soil, or other locallypermitted permeable material, and the interface between the disposalarea and the soil is where the secondary treatment process of thewastewater takes place becomes a biological mat (bio-mat). The bio-matshould be typically be maintained in an aerobic state for long termoperation of a wastewater disposal system to occur. Where aerobicconditions are not typically maintained, the bio-mat will thicken muchmore quickly and failure of the disposal area will result quicker than atypical aerobic state disposal bed.

In normally functioning septic disposal areas, the wastewater isnaturally and microbiologically processed as it passes through thebio-mat and subsurface fill material (or native soil) by aerobic andanaerobic bacteria and micro-organisms (bugs). The top few inches ofsand or soil develop into a bio-mat which bugs and other bacteria whichhelps digest the wastewater. These bugs will be both combination ofaerobic and anaerobic organisms. The effluent of a septic tank containssubstantial anaerobic bacteria, and unless the disposal area ismaintained in an aerobic state, the anaerobic bugs will flourish and thebio-mat will tend to thicken and the disposal area will clog prematurelywith anaerobic sludge.

Adequate air is typically available to supply aerobic bacteria withoxygen at the bio-mat interface of the secondary treatment area, since atypical disposal area is shallow and covered with grass which is apervious material. If the disposal area is affected by site specificconditions which do not allow for a shallow disposal bed covered withgrass, anaerobic condition can occur. For example, the site specificconditions may include, but are not limited to, the disposal area is toodeep in the ground, or underneath parking areas which prevent adequateoxygen from reaching the disposal bed; and/or the disposal area isinfluenced by leaky plumbing fixtures and/or by surface or subsurfacegroundwater conditions that hydraulically overload the disposal bedbeyond the hydraulic conductivity of the bio-mat.

The bio-mat for a septic system will typically remain adequatelypermeable for 10-40 years. In cases where disposal areas are adverselyaffected by one of the above, anaerobic conditions can occur in thedisposal area and resultant premature failure of the disposal area canoccur in less than 10 years.

It is known that the biochemical processing of wastewater is enhanced byflowing air or other active gas through secondary wastewater treatmentprocesses, and the temperature of the aerobic environment will affectthe aerobic activity rate. Typically, the air flows to or from auxiliarypipes in the soil run parallel to and spaced apart from perforatedlateral pipes so that the air can flow to or from the wastewaterdistribution laterals. The auxiliary pipes are either evacuated orpressurized relative to induce aeration of the surrounding area.Disposal areas aeration technology can be applied to new installationsor retrofitted onto old installations. The subject invention improvesthis known process, specific to onsite wastewater disposal, by allowingmultiuse lateral installations under and within the zone of treatment ofa secondary treatment area following a septic tank to providerejuvenating properties and continuous/intermittent long term aerationthrough the multiuse permanent installation laterals for air/fluidairwashing, backwashing, and long term aeration maintenance. The subjectinvention results in the ability to maintain a secondarytreatment/disposal area indefinitely by allowing cleaning out oftreatment/disposal areas by locally licensed waste haulers, thereforeminimizing environmental impacts of mining activities, and minimizinghazardous disposal volumes at local landfills for contaminated soiltypically removed from septic disposal systems. Licensed waste haulerstypically deliver the liquids and solids to local wastewater treatmentfacilities for tertiary treatment and ultimate disposal per state andlocal requirements.

Proper disposal area performance can be affected if the soil layer isthicker or less permeable over the leaching system. This will lead to arise of anaerobic bacteria in the bio-mat and a potential environmentalhazard when the disposal area fails and surfacing of effluent on theground, or backup of plumbing occurs.

In some disposal area installations, the soil is topped by a bituminouspavement or analogous material which is vastly different from soil, andwhich pavement has either limited permeability or uneven permeability,due to changes thickness, density, cracks, and so forth.

Thus, there is a need to provide a system to be able to maintain aerobicconditions in the disposal area and the bio-mat, specifically where thesystem properly aerates the bio-mat. Typically, previous aerationtechnology involves aeration of the disposal area by pressurization ofthe disposal area from above the bio-mat, this technology does notsignificantly improve the aerobic condition of the soil beneath thebio-mat where aerobic bacteria need to survive for long term operationof the disposal area. The present invention results in aerobicconditions beneath thin aerobic conditions where previous technologydoes not. The aerobic conditions are variably maintained by controllingthe amount of air and hence, oxygen flow is regulated with automatic ormanual on off operation of the blower. The blower aerates the soilbio-mat interface from below and as the air rises to the atmosphere, theoxygen in the air allows aerobic bacteria to thrive on either side ofthe bio-mat for sewage disposal systems.

SUMMARY OF THE INVENTION

The present invention is utilized for controlling and maintaining theaerobic environment under septic disposal areas, allowing forrejuvenation of clogged disposal areas, and providing enhanced aerobicactivity in the disposal areas with restricted aerobic activity and/orlimited permeable surface above the secondary treatment areas. Thisinvention allows for low rate aeration, and high rate air washing andfluid backwashing of functioning and malfunctioning sewage disposalinstallations which effectively rearranges, mechanically cleans andrestructures the soil to allow permeability to be restored andmaintained in the subsurface soil. In some instances, natural silica,sand or other benign durable natural spheroidal objects may be addedduring backwashing operations to improve the permeability of the soil.

The present invention is a system which prolongs the life of a disposalarea under a limited permeable environment, as well as correctsdefective existing systems by providing high quantities of air flow toboth sides of the disposal area bio-mat, which will provide enhancedbiological activity to reduce the bio-mat thickness, biologically removesludge, and provide long term low air flow/or other fluids and additivesto the zone of treatment, thereto to promote proper biochemicalperformance for an optimal and sustainable bio-mat thickness that allowsadequate permeability and provides enhanced wastewater quality to thelocal aquifer. Additionally, the air may be heated to provide a warm airflow to warm up the bio-mat for enhanced aerobic activity.

The present invention does not pressurize the disposal area. The airflows opposite to the direction of the wastewater. The present inventionis installed in site specific bored horizontal holes, and at moderatedepths greater than about 8 inches below the bio-mat interface,preferably between about 8 inches to about 24 inches below the bio-matinterface. Additionally, laterals can be placed greater than about 8inches from the perimeter of the bio-mat interface.

The present invention provides an aeration lateral system designed to besite specific for retro fitting to existing septic disposal areas, or asa new installations, to be a permanent intermittent air/fluid washingand intermittent or continuous low volume air or low volume heated airsupply system to periodically break up the biological clogging mat atthe interface of the disposal area and imported sand, or native soilfill under the disposal area. The lateral system is designed to providesite specific distribution of air/fluids to the wastewater disposalarea, with lateral spacing and air hole spacing varying based on theoperating conditions, type and size of disposal area being utilized.Retrofit lateral installations are performed by boring holes under thedisposal area and installation of the laterals into the bored holes.

The present invention provides a system to enhance aerobic activity andbio-mat control for new or existing septic disposal areas with limitedpermeable surfaces thereabove. The system includes a wastewater zone oftreatment located underneath a limited permeable surface; a series ofaeration laterals having tapered diffuser holes therethrough to providefor even air distribution therethrough, the series aeration lateralsextending about a bio-mat, the tapered diffuser holes have an insidediameter and an outside diameter, the inside diameter is smaller thanthe outside diameter; and a manifold attached to the pipes providing afluid to the series of aeration laterals. The fluid can be air andheated air. The system can further include a pump connected to themanifold to provide a flow of the air through the manifold. The systemcan include a vent pipe attached to the zone of treatment to allow airto escape from the zone of treatment.

The present invention further provides for a system to enhance aerobicactivity and bio-mat control for new and existing leaching fields. Thesystem includes at least one wastewater disposal lateral extending froma septic tank into a seepage pit, disposal field, or infiltrationchamber above a zone of treatment; at least one aeration lateralextending within the zone of treatment, the at least one aerationlateral is an elongated pipe having a sealed end and an attached end,the attached end is attached to a conduit supplying pressurized airtherethrough, the elongated pipe including a series of spaced aparttapered diffuser holes to allow air to escape therethrough; and an airsupply source attached to the at least one aeration lateral to providepositive air pressure through the at least one aeration lateral forairwashing and aerating said zone of treatment. The system can furtherinclude a vent pipe connected directly to the zone of treatment andextending above ground to provide venting to the atmosphere. The airsupply source can be a compressor, and the compressor passively heatsthe pressurized air and supplies the pressurized air to the at least oneaeration laterals. The distance between each diffuser hole can increasefrom the sealed end to the attached end to provide air distributionalong the length of the pipe. Further, the system can include asubsurface vault constructed of reinforced concrete, steel, fiberglassor polyvinyl chloride to house the air supply source therein.Additionally, a vent can supply air into the subsurface vault and intothe air supply source. At least one aeration lateral extends through thezone of treatment below the disposal area to aerate a bio-mat, and theaeration laterals including tapered diffuser holes therethrough fordistribution of air to the bio-mat.

Further, the present invention includes a method of aerating a bio-mat,including the steps of supplying air to an air supply source;compressing air through the air supply source; passively heating the airas air is compressed; supplying heated air to a series of aerationlaterals having tapered diffuser holes therethrough to provide for evenair distribution therethrough, the series aeration laterals extendingabout a bio-mat, the tapered diffuser holes have an inside diameter andan outside diameter, the inside diameter is smaller than the outsidediameter; and expelling air from the aeration laterals through thetapered diffuser holes, the air flowing from the zone of treatmentvertically upwards to the bio-mat to aerate the bio-mat.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a system formed in accordance with the subjectinvention.

FIG. 2 is a schematic of an aeration system formed in accordance withthe subject invention.

FIG. 3 is a schematic of a retro-fit aeration system in a parking lotfor a disposal bed formed in accordance with the subject invention.

FIG. 4 is a schematic of an aeration system for a seepage pit disposalarea formed in accordance with the subject invention with air andbackwashing lateral adjacent to and under a seepage pit.

FIG. 5 is a schematic of an aeration system for a seepage pit disposalarea system formed in accordance with the subject invention withvertical air and backwashing lateral adjacent a seepage pit.

FIG. 6 is a schematic of a system for a disposal bed under a parking lotor other impervious surface formed in accordance with the subjectinvention.

FIG. 7 is a schematic of sealing a septic tank outlet baffle formed inaccordance with the subject invention.

FIG. 8 is a schematic of a subsurface blower installation formed inaccordance with the subject invention

FIG. 9 is a cross section of a subsurface blower installation formed inaccordance with the subject invention.

FIG. 10 is a schematic top view of a bio-mat relative to a disposal bedinstallation formed in accordance with the subject invention.

FIG. 11 is a schematic of a horizontal borehole and methods ofpreventing air leakage through soil relative to a disposal bedinstallation formed in accordance with the subject invention.

FIG. 12 is a schematic of a lateral air discharge holes diffusers formedin accordance with the subject invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-12 show an aeration system 50 of the present invention fordisposal areas.

FIG. 1 shows septic system with a method for enhanced aerobic activityfor a disposal area 6. A disposal area 6 includes, but is not limitedto, disposal bed, seepage pit and the like. The septic system includes asource 1 of wastewater connected to connection pipes 3 which are locatedbelow ground level 2. The source of wastewater fed to the disposal areas6 can be from a variety of sources as know in the art. The wastewaterincludes any known wastewater, such as storm or sewer water as known inthe art. The connection pipes 3 connect the source 1 of the wastewaterto a primary treatment septic tank and/or aerobic treatment and/or pumptank 4. The connection pipes 3 also connect the tank(s) 4 to wastewaterdisposal laterals 5 which are perforated lateral pipes or infiltrationchambers which allow the wastewater to escape to the disposal area 6.The wastewater disposal laterals 5 can be surrounded by crushed stone toallow for the wastewater to percolate through the stone and into thezone of treatment 7. The zone of treatment 7 is the area where bothbiological breakdown and mechanical filtration system occurs.Alternatively, when using infiltration (hollow) chambers, stone is notnecessary and wastewater leaches into the soil below. Bio-mat formationoccurs at the bottom of the stone or infiltration chamber at the soilinterface at the top of the zone of treatment 7. This zone of treatment7 provides secondary treatment of the wastewater for traditional septicsystems. The improved aeration system 50 includes at least one aerationlateral 9 installed within the zone of treatment 7 and surrounded byimported sand or native soil to deliver fluid to the zone of treatment7. The fluid can include air, other gases, liquids or combinationsthereof. The effluent wastewater from primary treatment tank(s) 4 entersthe disposal area 6 through connecting pipe 3 and is distributed in thedisposal area 6 by the wastewater disposal laterals 5 and is distributedin the disposal area 6 downward through the crushed stone into the zoneof treatment 7 and into the zone of disposal 8, the wastewater isconsidered benign and environmentally safe for introduction into theenvironment. The zone of treatment 7 and zone of disposal 8 may beimported sand or native soil. FIG. 1 further shows a ventilation pipe 11which extends from the crushed stone 6 to the atmosphere. Theventilation pipe 11 includes a ventilation port 10 which is a minimum ofabout 24 inches above ground 2 (or as dictated by local building codesand to be above typical maximum snow depth). Additionally, a ventilationsupport 12 is supplied to support the ventilation pipe 11.

FIG. 2 shows the aeration laterals 9 attached to a manifold 15 and airsupply pump enclosure 14 attached extending from the manifold 15. Theair supply pump enclosure 14 includes a blower, compressor, air supplymember mounted therein. The air supply pump enclosure can be asubsurface vault which is designed to preferably warm the air a minimumof about 20 F degrees above ambient conditions at the discharge, andsupply long term continuous or intermittent warmed air supply throughthe diffuser holes 13 below the bio-mat at a maximum orifice outletpressure of 12.5 psi to prevent fracturing of soil. The aerationlaterals 9 include a series of perforated pipes which provide warmed airor other gases continuously or intermittently as necessary to the zoneof treatment 7 to enhance aerobic activity, for the purpose of bio-matreduction and control. The aeration laterals 9 are made from PVC orother plastic piping and range in diameter from about ½″ to about 4″.The length of the aeration laterals 9 depend on the size and operatingcondition of the disposal area 6. The aeration laterals 9 are preferablylocated directly below the bio-mat in the zone of treatment 7. Thediffuser holes 13 are sized and designed with a chamfer to more evenlydistribute air under the bio-mat, and prevent soil fracturing atpressures up to about 12.5 psi. The diffuser holes 13 are tapered atabout a 45° angle through the thickness of the pipe with a diameter ofabout 0.25 inches to diffuse the air flowing therethrough. The diffuserholes 13 are separated about the circumference at 90 degrees from eachother. The air can be applied at a high rate for airwashing so thatairflow upwards perpendicular to the biological clogging mat isperformed at a periodic rate sufficient to lift and/or break up theclogged soil bio-mat interface. Alternatively, air can be supplied at acontinuous or intermittent lower rate to warm the environment of thebio-mat and provide sufficient oxygen facilitate the growth of aerobicmicroorganisms in the zone of treatment 7. The air rate is site specificbased on hydraulic loading rate, soil permeability, and quality ofwastewater.

The air flow rate through the aeration laterals 9 is controlled tomaintain an orifice outlet pressure preferably below about 12.5 psiduring airwashing operations to prevent fracturing of the soil, and airpressure is preferably maintained typically below about 2.5 psi duringcontinuous or intermittent use for the purpose of warming the soil andcontrolling the thickness of the bio-mat. Each aeration lateral 9 caninclude an air control mechanism manual or automatic valve 17 to controland/or regulate to air flow through each aeration lateral, as shown inFIGS. 8 and 9. One end of the aeration laterals 9 is sealed off suchthat no air escapes with an anti-seep collar or boot 51. The other endof the aeration lateral 9 is attached to a manifold 15. The manifold 15is typically a larger diameter pipe made from the same materials as theaeration laterals 9. The manifold 15 range in diameter between about 1inch to about 10 inches. The manifold 15 can run perpendicular to theaeration laterals 9 or at an angle. One end of the manifold 15 is sealedoff preventing air from escaping therefrom. The other end of themanifold 15 has a compressor, blower, or other air supply attachedthereto. The air supply source provides air through the manifold 15 andaeration laterals 9 and out the diffuser holes 13. The air supply sourcecan be located above grade or underground. The air supply sourcepressurizes the system to various pressures based on whether theaeration system 50 is being utilized for airwashing purposes or forcontinuous or intermittent low air flow rates to maintain aerobicperformance of the disposal area system. Preferably, airflow rates forair/fluid washing is about 1-5 cubic feet per minute per square foot ofdisposal area system bio-mat area. Low flow to maintain aeration in thedisposal beds is about 0.001 to about 0.01 cubic feet per minute persquare foot of disposal area system bio-mat area.

FIG. 2 also shows an airtight rubber or other flexible gasket 37 can beinstalled around the aeration lateral 9 to prevent the leakage of air.An air diffuser 39 can be installed to assist with diffusing the air andpreventing the diffuser holes 13 from clogging with soil. The airdiffuser 39 extends about the exterior of each of the aeration laterals9. The air diffuser 39 can be a textile material formed into a woven,knitted, braided, mesh, or netted configuration. The air diffuser 39 canbe a formed from natural or synthetic fibers such as a woven cloth orpolymeric mesh.

FIG. 3 shows an alternative embodiment which is similar to the aerationsystem 50 shown in FIGS. 1 and 2 but the aeration laterals 9 extend atan angle, fanning out into the zone of treatment 7. Additionally, themanifold 15 and the air supply are in a subsurface enclosure 14. Thisallows for easy access to the air supply source forairwashing/backwashing which includes increasing air/fluid pressurethrough the aeration laterals 9 for a specific time frame to allow forbreak-up of sediment for malfunctioning systems. Various gaseous/fluidtransfers or other additives may be used in conjunction with thissystem. For example, a backwash pump may be used instead of the aircompressor to allow for liquid fluid transfer through the aerationlaterals 9 to clean out/treat/remove/break-up sediment. The use oflocally licensed waste hauler will be required to remove any wastewatercontaminated fluids or solids as a result of the air/fluid backwashingmaterials.

FIG. 4 shows a seepage pit 18 surrounded by crushed stone 20. A seepagepit 18 can be constructed with concrete, masonry block, or stone, andhas holes or gaps that allow wastewater to permeate through the sidewalls and bottom of the seepage pit 18 which develops a bio-mat andeventually ceases to operate as the bio-mat thickness grows over time.Two aeration laterals 9 are shown, although the number of laterals willbe site specific based on site constraints, thickness of bio-mat,quantity and quality of wastewater. One or more aeration lateral(s) 9extends directly under the seepage pit 18 and parallel thereto. Theother aeration lateral 9 extends at a diagonal and ends at the crushedstone 20.

FIG. 5 shows a seepage pit 18 which is surrounded by crushed stone 20. Aseepage pit 18 can be constructed with concrete, masonry block, orstone, and has holes or gaps that allow wastewater to permeate throughthe side walls and bottom of the seepage pit 18 which develops a bio-matand eventually ceases to operate as the bio-mat thickness grows overtime. Two aeration laterals 9 are shown extending vertically along theside perimeter of the seepage pit 18, although the number of aerationlaterals 9 will be site specific based on site constraints, thickness ofbio-mat, quantity and quality of wastewater. The aeration laterals 9 area distance of greater than about 8 inches from the outside sidewallsperimeter of the seepage pit 18 to allow for proper aeration of thewastewater.

FIG. 6 is the aeration system 50 of FIG. 1 in use for a less permeable,impervious ground surface like a parking lot or pavement where theground surface is not capable of transferring air from the atmosphere tothe soil below the impervious surface 19. FIG. 6 shows wastewaterdisposal laterals 5 surrounded by crushed stone 20. The ventilation pipe11 is directed connected to the crushed stone 20 to eliminate airpressure above the point of connection. The ventilation pipe 11 extendsfrom one side of the crushed stone 20 out to the atmosphere. Theventilation pipe 11 is capped with a ventilation port 10. Theventilation pipe 11 is made from PVC piping and ranges in size from 2inches to 12 inches based on the size of the disposal bed 53, andquantity of airflow. The ventilation pipe 11 is not pressurized as it isopen to the atmosphere. Additionally, the wastewater disposal laterals 5only supplies wastewater. Under normal circumstances, the wastewaterdisposal laterals 5 is not under any additional pressure and does notmix with air by aeration piping or a compressor. The aeration lateral 9is parallel to, adjacent, aligned and directly under the wastewaterdisposal laterals 5. The aeration lateral is spaced apart from thecrushed stone 20 and the wastewater disposal laterals 5 to allow fornatural migration and expansion of the air from the aeration lateral 9through the sub-ground as shown by vectors V. Vector V shows thedirection of the air flow through the soil. The aeration laterals 9 maybe installed below the groundwater elevation. The aeration laterals 9are typically placed 6 inches to 3 feet under the bio-mat. The aerationlaterals 9 are always under pressure to allow air to be pumped throughthe system and out the diffuser holes 13. FIG. 5 shows the pressurecurve in the soil. The highest amount of pressure (P) is at the point ofair flow from the aeration laterals 9. The pressure curve shows that theair pressure decreases as the air disperses through the soil and thecrushed stones 20. The air is vented through the ventilation pipe 11 andthe air is released to atmosphere which eliminates the air pressureabove the ventilation pipe 11, as shown by the pressure curve.

FIG. 7 illustrates a method of sealing a septic tank outlet baffle 54 toprevent escape of air and odor problems. The inlet baffle does nottypically need modification when this invention is installed. The outletbaffle 54 is manufactured with PVC or other plastic pipe and is cappedto prevent escape of air and odors from the septic tank during theaeration process. The vent cap 21 is a mushroom vent cap is similar toPolylok's Polyair™ Activated Carbon Vent Filter which is removable toallow access to the outlet pipe 3 from the primary treatment tank 4.Outlet pipe 3 must be sealed during periodic maintenance of the disposalbed with high volume air to prevent air from entering into andpressurizing the primary treatment tank. The primary treatment outletbaffles 54 act as a removable odor control vent to prevent pressurizingthe septic tank when the air is introduced into the disposal area 6.

FIGS. 8 and 9 illustrate the air supply pump enclosure 14 which isconstructed of high density non-corrosive polyethylene plastic, and hasan insulated lid 28 to increase thermal heating efficiency, and has thehighest ultraviolet light protection available such as the Polylok™ Inc.3008 series sump basin. The air supply blower is a regenerative turbinedesign sized to provide adequate air and discharge pressure for eachparticular installation, similar to Fuji Electric VFC seriesregenerative turbine blowers. The air suction line is protected from theprecipitation by a mushroom vent 22 and suction pipe 23 are properlysized to provide proper cooling to the thermally protected totallyenclosed fan cooled motor 25 of the regenerative turbine pump 26. Thisair supply source supplies pressurized heated air to the manifold 15 andaeration laterals 9 of the installation. The air 24 is designed totravel across the motor surface to help cool the motor prior to enteringthe air intake filter 27 and suction line 29 at approximately 180degrees orientation in the subsurface insulated enclosure with airflowacross the motor 25. The air intake takes the heated (motor cooling air)air from the enclosure and after compression and acceleration throughthe turbine housing, becomes further heated by the adiabatic process(otherwise known as heat of compression) by 10 to 50 degrees F. beforeentering the manifold 15, and aeration laterals 9. This heated air actsto heat the disposal area bio-mat and enhance aerobic activity in thebio-mat.

FIG. 10 illustrates the bio-mat thickness for a disposal bed 53treatment. FIG. 10 shows the level of infiltration interface 31 islocated between the stone and the soil subgrade at the top of the zoneof treatment 7. The level of infiltration interface 31 is where anorganic mat of aerobic and anaerobic bacteria will form the bio-mat 30which acts as a limiting factor for infiltration. The infiltration rateof the disposal area 6 is governed by the infiltration rate of thisbio-mat barrier which will determine the long term acceptance rate(LTAR) of the disposal area 6. The LTAR will decline over time as atypical increase in bio-mat 30 thickness will occur based on thecharacteristics of the wastewater, and the characteristics of the soilin the zone of treatment 7. The bio-mat 30 formation will extend upwardsa distance 33 into the stone of the disposal area 6 to the approximatelevel of high water elevation of the disposal area 6. The operatingcondition of a disposal area 6 can be monitored by the high levelelevation 33 and thickness 34 of the bio-mat 30. See Spreadsheet ForEstimating Long Term Acceptance Rate For On-Site Wastewater Systems InGeorgia, David E. Radcliff et al., Proceedings of the 2009 Georgia WaterResources Conference, April 2009, incorporated herein by reference.

A proper operating typical residential septic disposal area or bed has abio-mat 30 thickness 34 of about 1 inch to about 2½ inches when sand isutilized in the zone of treatment 7, and the sand has a permeability ofabout 6 inches to about 20 inches per hour, and the hydraulic loadingrate to the disposal area size under 2 gallons per square foot ofdisposal area per day, and the disposal area has a septic tank sizedpreferably at a minimum of about 150% of the daily flow rate from thedwelling unit prior to discharge into the disposal area.

The level of infiltration 31 of the wastewater for a disposal area 6 isat the bottom of the disposal area 6 and the top of the zone oftreatment 7. The bio-mat 30 will begin to form at the level ofinfiltration interface 31 and the consistency and permeabilty rates ofthe bio-mat 30 can vary substantially based on hydraulic loading rate,the composition of the wastewater, and the type of soil in the zone oftreatment 7, and the subsurface groundwater level. Under normaloperating conditions, the bio-mat 30 formation will extend down into thezone of treatment 7 at a distance 32 below the level of infiltration 31of about 0.5 inch to about 1.0 inch; and the bio-mat 30 formation willextend upwardly above a distance 33 above the level of infiltration 31of approximately about 0.5 to about 1.5 inches to the top 35 of thebio-mat 30. The total thickness 34 of a bio-mat 30 is about 1.5 inchesto about 2½ inches. Based on the hydraulic conductivity of the bio-mat30, the hydraulic loading rate to the disposal area 6, and the type ofsoil in the zone of treatment 7, and the groundwater elevation, failureof the disposal area 6 will ultimately result when the water level inthe disposal area 6 becomes equal to or higher than the distance betweenbottom of the laterals and the level of infiltration 31 (shown asdistance 36). This causes a backup of the plumbing which is about 10 toabout 40 years after the initial installation of the septic disposalarea based on the quality of wastewater and the type of soil in the zoneof treatment 7. Failure of the disposal area 6 can occur between about 1to about 10 years where insufficient aeration of the disposal areas 6results in anaerobic conditions at the level of infiltration 31.

FIG. 11 is a schematic of the horizontal borehole 40, the woven clothair diffuser 39 and the methods of preventing air leakage through soil.When installing a borehole 40 under a disposal area 6, temporaryexcavation 16 is necessary to lower the boring equipment to the properelevation. Unless precautions are taken, air leakage will occur throughend of the lateral 9 and through the soil in the temporary excavation.An airtight rubber or other flexible gasket 37 can be installed aroundthe lateral to prevent the leakage of air out of the borehole 40. Priorto installation of the gasket 37, the end 38 of the borehole 37 shouldbe properly compacted, or filled with airtight foam or other sealantbehind the gasket 37. The air woven cloth air diffuser 39 should beinstalled so that the end of the cloth does not pass through gasket 37.The temporary excavation 16 must be properly compacted to furtherprevent any air loss out of the ends of the aeration lateral 9.

FIG. 12 is a cross sectional view of a lateral 9 showing the geometricshape of the diffuser hole 13 through the thickness of the lateral andthe woven sock diffuser 39 extending about the lateral 9. The diffuserhole 13 is tapered to provide lower air velocity and pressure than ahole with no taper. The inside diameter d_(i) of the diffuser hole 13 issmaller than the outside diameter d_(o).

The amount of air existing the diffuser hole 13 of the laterals 9 willbe based on airflow equations. By increasing the hole size (d_(i) andd_(o)) adjacent to the lateral 9 and soil interface 41, a taper of thediffuser hole 13 provides the same quantity of air at a lower pressureat the soil lateral interface 41. The installation of the woven sockdiffuser 39 further diffuses the air and further protects the soil inthe zone of treatment 7 from fracturing due to high pressures and highairflow velocities.

Preferably, the orifice sizing of the diffuser holes 13 is about ¼″diameter hole on the interior of the pipe or inside diameter d_(i); andpreferably about ½″ at the outside of the pipe or outside diameterd_(o). The diffuser hole 13 can be larger depending on the width andlength of the lateral 9 used. The opening of the diffuser hole 13, istapered at a 45 degree angle A to diffuse the air and lower the velocityof the air against the lateral 9 and soil interface 41. The diffuserholes 13 are preferably spaced 180 degrees apart every 8 inches withadjacent holes 13 alternating 90 degrees every 8 inches to provideuniform airflow in the entire zone of treatment 7.

The aeration system 50 of the present invention may be installed for usewith a septic disposal area 6 as a new or as a retrofit installation.The steps of installation for retrofit include digging a trench oraccess pit near the existing septic disposal area and boring holesbeneath or into the zone of treatment. The boreholes may be horizontal,vertical, or directional to allow installation of permanent air lateralsadjacent to and under existing disposal areas. The pipes are insertedinto the bored holes which will serve as the aeration laterals. Installthe air laterals parallel to the clogged soil interface with holes orother air diffusers releasing air perpendicular to the air lateral andperpendicular the clogged soil interface. The aeration laterals have aplurality of holes drilled therein and spaced apart at an interval thatallows for uneven air distribution. Connect the aeration lateralstogether by a manifold fitted with pressure gauges. The manifold istypically constructed of PVC piping. A connection to a compressor isavailable to the manifold to allow for high rate air backwashing, and/oralternatively to connect a backwash pump to the manifold to backwash thedisposal area. Water or other fluid backwashing is typically completedwith clean water to flush out the bio-mat and gently expand the soil toallow for improved permeability, and is typically at a rate of 1.0 to5.0 gallons per minute per square foot of bio-mat area, with carefulconsideration of site specific soils properties to maximize the flow butprevent expansion of the soil more than 5% or cause excessive channelingof the soil. To predict the amount of headloss anticipated by thebackwash flowrate, from water treatment filter technology, severalequations have been developed to describe the flow of clean waterthrough a porous medium. Carman-Kozeny equation used to calculate headloss is as follows:

$h = \frac{{f\left( {1 - \alpha} \right)}{Lv}_{s}^{2}}{\varphi \; \alpha^{3}d\; g}$$h = \frac{{{fp}\left( {1 - \alpha} \right)}{Lv}_{s}^{2}}{\varphi \; \alpha^{3}d_{g}g}$$f = {{150\frac{\left( {1 - \alpha} \right)}{N_{g}}} + 1.75}$$N_{g} = \frac{\varphi \; {dv}_{s}\rho}{\mu}$

where, h=headloss, m

f=friction factor

α=porosity

φ=particle shape factor (1.0 for spheres, 0.82 for rounded sand, 0.75for average sand, 0.73 for crushed coal and angular sand)

L=depth of filter bed or layer, m

d=grain size diameter, m

v_(s)=superficial (approach) filtration velocity, m/s

g=acceleration due to gravity, 9.81 m/s²

p=fraction of particles (based on mass) within adjacent sieve sizes

d_(g)=geometric mean diameter between sieve sizes d₁ and d₂

N_(g)=Reynolds number

μ=viscosity, N-s/m²

The head loss and the backwash rate are related to the rate at which airor water is forced from below or adjacent to the bio-mat, and the headloss calculation is necessary to properly size the lateral diameter, andhole size, and the separation between holes. The backwash rate istypically much greater than the percolation rate of the soil. Thebackwash rate can be adjusted to allow for soil expansion as desired torestore permeability of overly compacted soils, soils clogged withbiological or other deposits which limit the permeability rate.

The subsurface soil rise rate is the speed at which water rises upthrough the ground during backwashing. This is another way of measuringthe backwash rate. During backwashing, the water pushes the subsurfacesoil up until it is suspended in the water. The height to which themedia rises during backwashing is known as the subsurface soilexpansion. For example, if the laterals are 24 inches deep beneath thebio-mat, during backwashing the soil may rise 1.2 inches duringbackwashing. This is a 5% subsurface soil expansion:

Subsurface soil expansion=((new Depth−Old Depth)/Old Depth)×100%

The step of connecting an air compressor or other air source to thelaterals provides air backwash supply, at a rate which is site specificcubic feet per minute of air (about 0.5 to about 5 cfm per sq ft) persquare foot of disposal area, to temporarily break up the cloggedsurface. Airwashing is typically necessary prior to completion of wateror other fluid backwashing to prevent channeling of soils. Addition ofoptional chemicals, and/or aerobic bacteria as allowed by local rulesand regulations to aid in the reduction anaerobic biomass formation andcreation of a healthy aerobic disposal system may be utilized in sitespecific instances. The laterals can also be utilized for continuous orintermittent low rate of air, water or other fluids through the lateralsto facilitate aerobic organisms to thrive in the disposal area, or aidin soil permeability remediation efforts as necessary. In someinstances, natural silica sand or other benign natural spheroidalobjects may be added during backwashing operations to improve thepermeability of the soil.

The aeration system of the present invention may be installed for a newseptic system. The steps of installation include installing aerationpipes in the zone of treatment, installation of a boot for sealing thepipe and preventing leakage of air and fluids, connecting the aerationpipes to a manifold with pressure gauges for each aeration line, andconnecting a pump to the manifold to provide constant or intermittentairflow to the septic system.

In either retrofit or new installations, venting of the clean stone,seepage pits and/or infiltration chambers shall be through a specialvent one-way vent mounted above or on the septic tank outlet or at a jobspecific preferred location such as adjacent to shrubs or otherlandscape, on a tree, light pole, or through a peat filter. Installationof the vent system prevents pressurization of the disposal area to lessthan 8 inches of water column, or as required by site specific (septictank effluent baffle depth, etc.) requirements. The vent is sized anddesigned to prevent the need for an aerobic interface between the stoneand the ground surface above, therefore allowing disposal areas tobetter operate under paved parking lots and other impervious or nearlyimpervious building construction activities.

Periodic maintenance of the disposal areas includes monitoring thedisposal efficiency of the disposal area and applying periodic high rateair introduction, low continuous, or other air flow adjustments toincrease or maintain better efficiency of operation. Periodicmaintenance also includes monitoring of biological activity of bacteriaand other microscopic and larger organisms in the disposal area and caninclude reseeding the area with appropriate bacteria, other microbes orother organisms to reduce, grow, or maintain an appropriate biomass inthe disposal area.

The invention being thus described, it will now be evident to thoseskilled in the art that the same may be varied in many ways. Suchvariations are not to be regarded as a departure from the spirit andscope of the invention and all such modifications are intended to beincluded within the scope of the following claims. Further, any of theembodiments or aspects of the invention as described in the claims maybe used with one and another without limitation.

What is claimed is:
 1. A system to enhance aerobic activity and bio-matcontrol for new or existing septic disposal areas, the new or existingseptic disposal areas including one or more wastewater disposal lateralssurrounded by crushed stone, the system comprising: a series of aerationlaterals having tapered holes therethrough to provide for airdistribution therethrough, said aeration laterals extending below thecrushed stone; and a manifold attached to said aeration lateralsproviding a fluid to said aeration laterals, whereby, said aerationlaterals introduce fluid upwardly to the crushed stone.
 2. The systemaccording to claim 1, wherein said fluid is air.
 3. The system accordingto claim 2, where said air is heated air.
 4. The system according toclaim 1, further including a pump connected to said manifold to providea flow of said fluid through said manifold.
 5. The system according toclaim 4, wherein said fluid is air, and said pump is a compressor. 6.The system according to claim 5, wherein said compressor passively heatssaid air and supplies said heated air to said aeration laterals.
 7. Thesystem according to claim 1, wherein the distance between each holeincreases in a direction towards the manifold to provide airdistribution along the length of at least one of said aeration laterals.8. The system according to claim 1, further including a ventcommunicating with the crushed stone to allow air to escape from thecrushed stone.